This invention relates to new boron-containing heterocyclic compounds, metal derivatives thereof, and methods for producing the compounds and metal derivatives. The invention further relates to lubricating oils and additives for use therein, and particularly to lubricating oils containing extreme pressure, anti-wear and friction-reducing additives.
Anti-wear, friction reducing and extreme pressure or "E.P." additives, as they are commonly called, are chemicals which are added to lubricating compositions to reduce friction and reduce or prevent destructive metal-to-metal contact in the lubrication of moving surfaces. Lubricating oils provide good lubrication between moving surfaces in contact with each other, as long as a film of said oil is maintained between the relatively moving surfaces. This particular kind of lubrication is commonly termed "hydrodynamic lubrication". However, when pressure and/or rubbing speeds between moving metal surfaces are such that the film of lubricating oil is no longer intact, metal-to-metal contact and wear occur over a significant portion of the previously lubricated area. Destructive metal-to-metal contact, due to lack of lubrication under extreme conditions, manifests itself in different forms such as scoring, welding, scuffing, ridging, rippling, rapid wear, and in some cases deformation or complete destruction of the metal components.
Extreme pressure, anti-wear and friction reducing lubricating additives prevent destructive metal-to-metal contact, under boundary lubrication conditions, by adsorption or reacting with relatively moving metal surfaces to form an adherent, protective film of compounds. This film acts in the capacity of a "boundary lubricant" and performs the function of lubrication when metal-to-metal contact occurs. Boundary conditions and boundary lubricant refer to the conditions and a suitable lubricant relating to the combination of applied load, fluid viscosity and rubbing speed, which do not allow hydrodynamic lubrication to exist. Hydrodynamic lubrication exists when a film of lubricant maintains separation between lubricated surfaces.
Many extreme pressure and anti-wear agents are oil soluble or easily dispersed as a stable dispersion in oil. Many of the E.P. agents which provide high load capacity are chemically reactive, containing chlorine, sulfur or phosphorus which react with metal surfaces.
It has now been discovered that certain oil-soluble or dispersible boron or metal-boron derivatives prepared as described herein, when added to lubricating oils or grease not only improve the ability of the lubricant to prevent seizure of the parts being lubricated but in addition greatly reduce the amount of friction and wear of such moving parts. Thus, a new family of extreme pressure and anti-wear compounds which are boron derivatives and/or reaction products of boron derivatives and metal salts thereof have been synthesized as described further herein.
It is well recognized in the petroleum industry that boron containing compounds are desirable additives for lubricating oils. One such boron containing compound is disclosed in U.S. Pat. No. 3,224,971 to Knowles et al. which relates to intracomplexed borate esters and to lubricating compositions containing said esters. The borate esters are organo-boron compounds derived from boric acid and a bis(o-alkylphenyl) amine or sulfide. These compounds are described as additives for lubricating oils.
Another boron ester composition is described in U.S. Pat. No. 3,269,853 to English et al. which discloses a boron ester curing agent which consists of a cyclic ring structure containing boron, oxygen, nitrogen, carbon and hydrogen.
It is an object of the present invention to provide a novel boron containing heterocyclic compound having extreme pressure, anti-wear and friction reducing properties for use in lubricating oils.
Another object of the invention is to provide a method of producing boron containing heterocyclic compounds.
Yet another object of the invention is to provide an improved lubricating oil having improved extreme pressure, anti-wear and friction reducing properties.
Other objects and advantages of the invention will be apparent from the following description.